demeanor vs mien

demeanor

noun
  • The social, non-verbal behaviours (such as body language and facial expressions) that are characteristic of a person. 

mien

noun
  • Demeanor; facial expression or attitude, especially one which is intended by its bearer. 

  • A specific facial expression. 

How often have the words demeanor and mien occurred in a corpus of books? (source: Google Ngram Viewer )